Two-stroke internal-combustion motor with scavenging and expulsion through ports in the cylinder



Nov. 27, 1928. 1,6933% 1'. v. HEMMING N TWO-STROKE INTERNAL COMBUSTION M0 W SGAV ING AND I EXPULSION THROUGH PORTS IN LINDE Filed F Patent Nov. 27,, 1928.

. rate ream TOBKILD V ALDEMAB HEMMINGSEN,- OF COPENHAGEN, DENMARK.

TWO-STROKE INTERNAL-COMBUETION MOTOR WITH SGAVENGING AND EXPULSION I THROUGH PORTS IN THE CYLINDER.

Application filed February 21, 1927, Serial N01 169,945, and in Denmark May 12,

This invention relates to an improvement in two stroke internal combustion engines with scavenging and expulsion through ports in the cylinder, of the kind in which the .expulsion ports are arranged in one group, while the scavenging ports are arranged in two groups symmetrically situated in relation to a plane passing through the cylinder axis and the centre, of the exhaust ports, the said two groups of scavenging ports consisting in a number of channels.

- The invention consists in a special arrangement of the said channels, by which an eiiec-. tive scavenging ofthe whole cylinder volume is obtained, and in connection with this arrangement, a shaping of the piston and the cylinder cover into a suitable form so as to correspond with the said arrangement,

The invention is illustrated in the drawing in which Fig. 1 shows in cross section a cylinder comprising an example of a performance of the arrangement according to the invention,

Fig. 2 shows the same cylinder in longitudinal section at right angles online A-B in Fig. 1 and looking in the direction indi: cated by the arrow 9,

Fig. 3 shows the same cylinder .in longitudinal section on line A-B in Fig. 1,

Fig. 4 shows part of acorresponding section through a modified construction, and

Fig. 5 shows the same in cross sectionon line CD in Fig. 4.

In the drawings a indicates the cylinder, 6 the piston rodand c theexhaust ports. It will be seen from Fig. 1 that the scavenging ports f are arranged in two groups symmetrically situated in relation to the plane indicated by the line AB which passes through the cylinder axis and the centre of the exhaust ,ports a.

The scavenging ports 7 consist in a number of channels separated by ribs and of such a direction that their central lines, which two and two intersect each other in the plane of symmetry Are-B, will meet in this plane of symmetry at points that are opposite to the.

, exhaust ports a in relation to the piston rod 6. The central lines of the channels situated nearer the exhaust ports a" will intersect each other directly behind the piston rod 6 while the more distant channels, as seen from the exhaust ports 0, have such a direction that T their central lines will intersect each other very near the cylinder wall. The central lines of the remainder of the channels will intersect each other in points that are evenly distributed over the intermediate distance, as Wlll appear from Fig. 1.

In connection with the above described arrangement the piston t is shaped in a special manner. In Fig. 2 the piston is seen from outside in its upper or inner dead centre position, while the cylinder is shown in section. It is assumed that a double acting engine is concerned, and the piston rodb is provided with ta1l rod. The piston head is curved towards a horizontal deflector 7c in both ends, the said deflector extending from a boss 1- on the piston and from the side of this boss that is opposite to the side nearest the exhaust ports 0, so that 1t'1s situated centrally between the two groups of scavenging ports f. In the position of the p1ston as shown in Fig. 2 the scavenglng air flows out through the scavenging ports f, and this scavenging air stream will then by means of the deflector is be made to flow longitudinally in the cylinder as indi- "cated by the arrows m and will flow downwards through one half of the cylinder and upwards through the other half (see also -Fig. 3) and will then pass out through the exhaust ports 0 so that an effective scavengmg of the whole cylindervolume is obtained. To further ensure the correct guiding of the scavenging air two deflectors p and g on thepiston head and similar to the deflector 7c are provided, which deflectors p and g are arranged symmetrically in relation to the line A--B and forming a suitable angle tothis plane, more preferentially so that theylneet the edge of the scavenging ports nearest to the exhaust ports 0, see Fig. 1.

Projections may advantageously be formed in the cylinder cover, of such a nature that they correspond with the pockets formed in the piston tbetween the deflector 7c and the defiec-.

. tors p and q and exactly fit the shape of the piston, and so that, whenthepistonisinitsbottom position,'only so much play is left which suflices to meet the wear on the bearings. No projection is provided, however, to enter the third pocket between the deflectors p and g. The cylinder cover is here, on the contrary, provided preferentially with suitable grooves or hollow spaces 10 (see Fig.3) so that a compression space of suitable proportions is formed here. The whole of the quantity of air introduced into the cylinder will then be compressed in this space, and the fuel valve 4:

produced when the piston is in its bottom position, namely, between the cylinder cover and the bottoms of the three pockets between the deflectors is, p andig in the piston t, and in this case the total volume of the three spaces must be made to be suitable for the com ression.

'lhis construction is shown in igs. 4 and 5. Fuel valves 0), m and o are arranged in the cylinder cover opposite every one of the three compression spaces.

An arrangement according to the invention is of special advantage with double acting engines with a continuous piston' rod (provided with tail rodz). A similar result may, however, also be 0 tained where no piston rod is found in the cylinder, as is the case with single acting engines, or in the top end of vertical, double acting engines where the piston rod is provided with no tail rod.

1 claim:

. 1. A two-cycle internal combustion engine comprising a cylinder having a head, a piston working therein, said cylinder being provided with'piston controlled inlet ports for scavenging air and piston controlled exhaust ports, said exhaust ports being symmetrically arranged in a group in that part of the cylinder' remote from said head, extending through only a portion of the cylinder circumference, theaxis of symmetry of said exhaust ports and the cylinder axis defining a plane of symmetry, said inlet ports being arranged in two groups disposed in the remaining part of the cylinder circumference, symmetrically with respect to the said plane of symmetry, the directional axesof said inlet ports intersecting said plane of symmetry in points located in the space between air thereb the cylinder axis and that part of the cylinder wall op osite said exhaustports, and the sequence 0 .said intersecting points bein in'the same order as the sequence of the sai inlet ports, said points of intersection with said planebeing substantially evenly spaced apart, the incoming streams of scavenging meeting in said plane of symmetry, uniformly from the middle of the cylinder to said part of the cylinder wall.

' being provided with-deflectors comprising three radially arranged ridges dividlng the 2. A two-cycle internal combustion engine as claimed'in claim 1, the head of the piston piston head 1nto three distinct areas, one deflector being situated in said plane of symmetry in the loci of the points of intersection of the center lines of said inlet ports, the other two deflectors. being situated symmetrically with reference to said plane of symmetry, and constituting with said firstmentioned deflector and with the piston, two

,haust ports, said exhaust ports being symmetrically arranged in a group in thatrpart of the cylinder remote from said head, extending through only a portion of the cylinder circumference, the axis of symmetry of said exhaust ports and the cylinder axis defining a plane of symmetry, said inlet ports being arranged in two groups disposed in the remaining part of the cylinder circumference, symmetrically with respectlto the said plane of symmetry, the directional axes of said inlet ports intersecting said plane of symmetry in points located in the space between the cylinder axis and that part of the cylinder wall opposite said exhaust ports, and the sequence of said intersecting points being in the same order as the sequence of the said inlet ports, said points of intersection with said plane being substantially evenly spaced apart, the head of the piston being provided with deflectors comprisingthree radially ar-' ranged ridges dividing the piston head into three distinct areas, one deflector being situated in said plane-of symmetr in the loci of the points of intersection of t 1e center lines of said inlet ports, the other two deflectors being situated symmetrically with reference to said plane of symmetry, and constituting with said first-mentioned deflector and with the piston, two symmetrically dis osed angu- V ing the volumes of said pockets when the piston is in its upper dead center pdsitiom-leaving a third pocket, disposed between the two second mentioned deflectors and that part of the cylinder wall on the same side as the exhaust air ports to constitute a combustion chamber, anda fuel valve located in the c linder head communicating with said third pocket.

4. A two-cycle internal combustion engineas claimed in claim 3, the cylinder head being povidedwith cup-shaped wells.

5. A two-cycle internal combustion engine compftilslng a cylinder having a head, a piston wor g therein, said cylinder being provided with piston controlled inlet ports forscaveng ing an and piston controlled exhaust ports, said exhaust ports being symmetrically arranged in a group in that part of the cylinder remote from said head, extending through only a portion of the cylinder circumference,

meacoo the axis of symmetry of said exhaust ports and the cylinder axis defining a plane of symmetry, said inletports being arranged in two groups disposed in the remaining part of the cylinder circumference, symmetrically with.

respect to the said plane of symmetry, the directional axes of said inlet ports intersecting said plane of symmetry in points located in the space between the cylinder axis and that part of the cylinder wall opposite said exaust ports, and the sequence of said intersecting points being in the same order as the sequence of the said inlet ports, said points of intersection with' said plane being substantially evenly spaced apart, the incoming streams of scavenging air thereby meeting in said plane of symmetry, uniformly from the middle of the cylinder to said part of the .cylinder wall, the head of the piston being provided with deflectors comprising three radially arranged ridges dividing the piston head into three distinct areas, one deflector bein situated in said plane of symmetry in the oci of the points of intersection of the center lines of saidinlet ports, the other two deflectors being situated symmetrically with reference to said lane of symmetry, and constituting with said first-mentioned deflector and with the piston, two symmetrically disposed angular pockets, each one of said pockets extendingover one group of inlet ports, the cylinderhead being flat and form- I ing with the deflectors on the piston three the piston is in its up er dead center osi- Y combustion chambers between the piston head, cylinder walls and cylinder head when tion, a fuel valve in t e cylinder hea for scavenging ports, sai exhaust ports being arranged in a group in that part of the cylin- -wor vided with piston controlled inlet orts for be each of said combustion chambers.

6. A two-cycle internal combustion engine comgrnising a cylinder having a head, a piston g therein, said cylinder being proair'and piston controlle exhaust symmetricallyplane of symmetry, said inlet ports being arranged in two groups disposed in the remaining part of the cylinder circumference, symmetrically with respect to the said plane of symmetry, the directional axes of said inlet ports intersecting said plane of symmetry in points located in the space between the cylinder axis and that part of the cylinder wall opposite said exhaust ports, and the sequence of said intersecting points being in the same order as the sequence of the said inlet ports, saidpoints of intersection with said plane being substantially evenly spaced apart, the incoming streams of scavenging air thereby meeting in said plane of symmetry, uniformly from the. middle of the cylinder to said part of the cylinder wall, the head of the piston being provided with deflectors comprising three radially arranged ridges dividing the piston head into three distinct areas, one deflector being situated in said plane of symmetry in the loci of the points of intersection of the center lines of said inlet ports, the other two deflectors being situated symmetrically with reference to said plane of symmetry, and constituting with said first-mentioned deflector and with the piston, two symmetrically disposed angular pockets, each one of said pockets extending over one group of inlet ports, the cylinder head being provided with ridges matching with the deflectors on the piston, three combustion chambers being thereby constituted between the piston head, cylinder wall and cylinder head when the piston is in its u per dead center osition, said cylinder hea being provided with fuel valves, one for each of said combustion cham- In' testimony whereof I' aflix my signature.

Tommi) VALDEMAR HEMMINGSEN. 

